/Engine/Source/Runtime/Engine/Public/AnimationRuntime.h
Accumulate a MeshSpaceRotation Additive pose to a local pose. Rotations are NOT normalized
static void AccumulateMeshSpaceRotationAdditiveToLocalPose ( [FCompactPose](API\Runtime\Engine\FCompactPose) & BasePose, const [FCompactPose](API\Runtime\Engine\FCompactPose) & MeshSpaceRotationAdditive, [FBlendedCurve](API\Runtime\Engine\Animation\FBlendedCurve) & BaseCurve, const [FBlendedCurve](API\Runtime\Engine\Animation\FBlendedCurve) & AdditiveCurve, float Weight )